A. Field of the Invention
The device of the present invention generally relates to the field of strain gauge pressure transducers and, more particularly, to a new and improved mounting arrangement for the pressure-sensing beam element of the transducer which permits the beam to follow movement of the diaphragm very accurately and without introducing distortions or internal stresses which normally interfere with the accurate measurement of such movement.
B. Description of the Prior Art
In the measurement of pressure, one of the more efficient and effective methods is the utilization of strain gauges and electric current. Many strain gauge pressure transducers have utilized the movement of a pressure sensitive diaphragm which is connected to a pressure-sensing beam by means of a mechanical linkage. Strain gauges positioned on opposite sides of the beam are employed to develop a suitable output signal. These arrangements have generally suffered from a so-called non-linearity effects in which the stresses set up in the mechanical linkage prevent the exact output signal from being repeatably produced as input pressure is moved up and down, similar to the well known hysteresis effect in magnetic circuits. One such arrangement is shown in U.S. Pat. No. 3,303,451 wherein a double-cantilever beam arrangement is provided which is mechanically connected to the center of a very small diaphragm. However, this double-cantilever beam and mounting arrangement introduces nonlinearities due to so-called membrane forces which prevent the output signal from being linearly proportional to strain at relatively high strain levels.
Certain prior art pressure transducers have employed an integral beam-diaphragm arrangement so that movement of the diaphragm is accurately imparted to the beam element and the above-described non-linearity effects are minimized. Examples of such integral beam-diaphragm transducers are shown in U.S. Pat. Nos. 2,979,680; 3,035,240; and 3,520,191. While these arrangements are generally suitable for their intended purpose, the integral beam and diaphragm in these transducers inherently limits the pressure range which can be covered.